Always make a depression with a center punch before drilling into metal. This will give the drill bit something to bite into instead of sliding all over the place.

Lay one of your discs on a hard stable surface.

Place your punch on the mark you made with your marker.

Hammer the punch head with a hard tap or two. The depression doesn't have to be deep.

Repeat with the other disc.

Step 4: Pierce the discs

A foot-controlled flex-shaft tool like a Foredom is your #1 choice for this job.

Unless you're a professional jeweler, you probably don't have one of these handy.

I used my Dremel with a drill press workstation attachment and a 0.8mm jewelers drill bit

Drill holes into the discs following either the drill press or flex-shaft tool instructions below.

Step 4 - Instructions for using a drill press setup:

Place a disc beneath your drill press on top of a scrap piece of wood.

Line up the bit with your mark.

Either hold the disc with your hand or (probably the wiser choice) tape it down to your board with 2 strips of masking tape - one on either side of the disc. You want the mark to be clear of tape so that the adhesive doesn't do anything to your metal when combined with the heat from drilling (unlikely, but just in case).

Bring the tip of the drill bit down firmly into your center punch dent.

Turn on the drill, then press the bit down until you drill right into the wood beneath your disc.

Remove the disc from your drill bit and repeat with the second disc.

Step 4 - Instructions for using a flexible shaft tool

Place a disc on top of a scrap piece of wood.

Tape both discs down to your board with 2 strips of masking tape each.

Line up the drill bit (firmly tightened into your flex-shaft tool) with your mark on one of the discs.
Hold it firmly in place in the center punch dent.

Brace your arm so that the bit doesn't skip, then turn on the drill. Drill down until you drill right into the wood beneath your disc.

Remove the disc from your drill bit and repeat with the second disc.

The pierced discs should look similar to these.

You can wipe the black marks off with rubbing alcohol but if your beads will be covering them up, then don't bother.